Enhanced Multiferroic Properties of Eu-Doped BiFeO3 Thin Films Derived from Rhombohedral-Tetragonal Phase Boundary

Eu-doped BiFeO3 multiferroic thin films were prepared using a sol-gel technique. The effect of Eu3+ ion substitutional doping on the multiferroic properties of BiFeO3 thin films was investigated in detail, revealing obvious enhancement of ferroelectricity and ferromagnetism. The enhanced multiferroic properties are attributed to phase boundary, where two phases with rhombohedral and tetragonal structure coexist. Both x-ray diffraction analysis and Raman spectroscopy confirmed that BiFeO3 thin films with 5% Eu doping (Bi0.95Eu0.05FeO3) undergo a phase transformation from a rhombohedral to tetragonal structure. Thus, it is suggested that there is rhombohedral- tetragonal phase boundary in Bi0.95Eu0.05FeO3 thin films. Additionally, the leakage current density of the thin films decreased under high electric field after Eu doping, which is attributed to a change of the leakage current conduction mechanism related to the formation of rhombohedral-tetragonal phase boundary. The present work provides an easy method to enhance the multiferroic properties of BiFeO3-based thin films.